#include <stdio.h>
#include <string.h>

int main(){
        int N, M;
        char A[51];
        int i, j, count;

        scanf("%d %d", &N, &M);
        count = N * M;

        for(i = 0; i < N; i++){
                scanf("%s", A);
                for(j = 0; j < strlen(A); j++){
                        if(A[j] == 'R') count--;
                }
        }
        printf("%d\n", count);

        return 0;
}